川中地区中三叠统雷口坡组构造特征及解释方法探讨

Structure styles analysis of Leikoupo formation in Mid-Trias-sic in central Sichuan basin

1. 四川石油管理局地调处物探研究中心,四川成都 610212;2. 成都理工大学,四川成都 610059;3. 西南油气田分公司川中气矿,四川遂宁 629000

Center of Geophysical Research, Geological Survey Office in Sichuan Oil Administrative Bureau, Chengdu 610212, China

通过对川中龙女寺地区的地质、测井、地震资料的综合分析,探讨了该区中三叠统雷口坡组的构造特征,即 在雷口坡组和下伏嘉陵江组的盐岩和膏岩等柔软地层的盐底辟构造作用及区域上的挤压构造作用共同影响下, 龙女寺地区雷口坡组形成了以坡坪式逆冲断层为主,密集的低幅度断弯褶皱相伴生的构造特征。当难以直接对 雷一²顶界反射对比时,可以选择同一组硬地层-雷一¹亚段与雷三¹至雷一²亚段的地震反射间的平行和亚 平行关系作为识别目的层位的辅助层。

This paper integrates geological, logging and seismic data of Longnusi survey incentral Sichuan basin, and discusses the structure styles and its cause of Middle Triassic Leikoupo formation of Longnusi in middle of Sichuan basin. Study shows that the structure style is roof slip contraction structure that primarily is ramp-flat thrusts accompanied by close fault-bend fold with low highness. The structure style is formed by conjunct action of regional compression and salt diapir, which is caused by soft salt and gypsum within Leikoupo formation and underlying Jialingjiang formation. Thus, the result can interpret sub-parallel relationship between the reflection of the top of Lei1¹,the reservoir zone, and the interior reflection within Lei3¹ to Lei1². Moreover,the relationship can be the main reference for recognizing Lei1¹ reflector. Meanwhile, it can reasonably interpret faults on the seismic profiles.